So I taped on a depron foam extension to the rudder to create more vertical stab area:

It sure isn't pretty..... Any bets on if it cured the wing rock? You have until the video uploads to make your predictions.

Steve

My guess is no, I've messed around with designing small flat wing foamies( I realize this may not relate to a balsa model with air foiled surfaces, but it's just my guess) and I found that extending the top of the rudder and therefore the height of the balance tab dosn't help wing rock. But if you extend the height of the vertical stab and keep or reduce the size of the balance tab it does seem to help wing rock. I like the experimentation on this plane, it's kind of brought this thread back to life although not quite as entertaining.

Hard to tell there when you're just going around in circles. Can't really see a right wing drop when you're constantly turning left..

How did it feel?

I think if you compare the two videos the difference is night and day.. I did do one right hand circuit in the vid but for some strange reason I always feel more comfortable going left when harriering, not just with the slick, with all my planes.

the limitations of the flight envelope in the vid are due to me, not the model.

If 'felt' 100% better, maybe not quite as stable as the EF edge but not far off.

I think if you compare the two videos the difference is night and day.. I did do one right hand circuit in the vid but for some strange reason I always feel more comfortable going left when harriering, not just with the slick, with all my planes.

the limitations of the flight envelope in the vid are due to me, not the model.

If 'felt' 100% better, maybe not quite as stable as the EF edge but not far off.

It definitely looked much better than the first video. I think you probably have found a few, of an unknown number, of design flaws that contribute to the poor post stall handling... Props on the experiment! Don't you wish HK would have done these trials and addressed these issues before releasing this plane!

Does this induce any unwanted coupling in KE flight? If not it seems you have made a silk purse from the proverbial sows ear. Nice job, now all you need is some balsa, strip the covering off, add the extension or build a new one and put some covering on and your good to go. The only problem is if you value your time off like I do I would rather be flying than fixing the problem. But if you like to fool with it and already have the plane then what the heck, looks like the results are well worth it. If I already had the plane I would do it.

Care to share the dimensions of the rudder extension, 'cause I'm going to cut some depron RIGHT NOW!

ok.. it was 3mm depron, it extended roughly 75-80mm in height and maybe 35mm out the rear tapering to zero at the bottom of the rudder.. I've attached a better photo.

After the video flight I trimmed the foam down to something that looks a lot better, the idea being that once I find the smallest size that still works I'll build a new rudder. The size that I trimmed down to was 55mm high and 10mm at the rear. Unfortunately some wing rock came back but it was still a lot better, it's probably going to be a compromise between best stability and still looking reasonably ok.

If anyone else wants to experiment with different sized and shapes of extension that would be cool. the wind came up for me and it was pointless testing any more.

I'll upload a vid of the second flight with the trimmed down extension.

PS.. I taped a bit of 1.5mm carbon rod extending over the leading edge of the depron and over the leading edeg of the balance horn... this stiffened the foam up a bit.

The extension was to flimsy to test in high speed flight but I didn't notice any undesirable effects other than looking butt ugly. In the ideal world I'd extend the fixed part of the vertical stab but that would be a lot of work.